Generally, techniques of treating textile goods, paper goods or the like with a water- and oil-repellent composition to impart a water- and oil-repellency or a water- and oil-resistance to their surfaces, are widely used in the field of industrial materials including daily clothing, sports clothing, umbrellas, tents, interior goods, wrapping papers or the like.
As a water- and oil-repellent composition, there is known an aqueous dispersion having a polymer containing a polymerization unit based on a monomer having a polyfluoroalkyl group (hereinafter referred to as “Rf group”) dispersed in water or a mixed solvent of water and an organic solvent (hereinafter referred to as “aqueous medium”).
As a method for preparing such an aqueous dispersion, there is known a method of emulsion-polymerizing a monomer having an Rf group or a method of emulsion-dispersing a polymer containing an Rf group in an aqueous medium with an emulsifier. The aqueous dispersion thus obtained is blended with various additives, if desired.
Heretofore, various water- and oil-repellent compositions have been studied and worked to improve water- and oil-repellency, to improve durability to washing or abrasion, and to improve water pressure resistance or oil resistance. Also, various studies have been made to improve applicability to synthetic fibers such as polyester, nylon, acryl or the like, and natural fibers such as cotton, wool, silk or the like, and various proposals have been made with regard to monomers, surfactants, organic solvents, and the like.
Recently, in view of preservation of the environment, safety and health, a water- and oil-repellent composition has been changed from one using an organic solvent to one using an aqueous medium. Also, it is demanded to develop a water- and oil-repellent composition not containing a polymer containing a polymerization unit having a halogen atom (except for a fluorine atom).
Further, from economical viewpoints, it is demanded to develop a water- and oil-repellent composition capable of imparting water- and oil-repellency or water- and oil-resistance in a small amount, a water- and oil-repellent composition capable of achieving a water- and oil-repellent effect at a low heat treatment temperature, and a water- and oil-repellent composition capable of providing a high production yield, which is less influenced by processing conditions. Also, it is demanded to provide water- and oil-repellent compositions which satisfy various customers' needs. For example, it is demanded to develop a water- and oil-repellent composition excellent in water- and oil-repellent durability at the time of washing with water and drying by a tumbler dryer as a dry cleaning system using water and a domestic tumbler dryer have been spread. In order to improve such a durability, there is widely used a treating method of using a binder such as methylol melamine resin or blocked isocyanate resin and its catalyst in combination with a water- and oil-repellent composition obtained by copolymerizing a (meth)acrylate having an Rf group with vinyl chloride, vinylidene chloride or the like. However, they are not satisfactory in view of influence of the above-mentioned organic chlorine compound to the environment, complexity of treating method, hard feeling of processed cloth, economical viewpoint or the like.
Also, methylol melamine resin is not preferable in view of environmental safety since it generates formalin, and use of blocked isocyanate resin is limited since it makes a treated material yellowish. Further, when using these binders, stability of a diluted solution at the time of processing is lowered and troubles such as settling of resin or contamination of a treated material by generation of a gel-like material are caused.
An object of the present invention is to provide a water- and oil-repellent composition excellent in safety and preservation of the environment and excellent in washing durability.